1. Field of Invention
This invention is concerned with apparatus for determining the distance of one object relative to another and more particularly to such apparatus wherein one object functionally includes an active beacon and the other object functionally includes a solid state imaging device.
2. Description of the Prior Art
It is well known that distance measuring or ranging may be done employing a video camera resolving cooperative active beacons. In the most general case, triangulation and a priori knowledge of the beacon geometry permits azimuth, elevation and range to be calculated if the other three degrees of freedom (roll, pitch, yaw) are known and restricted.
The performance of the system is dependent upon the accuracy with which the centroid of each imaged light spot from each beacon may be determined. In the prior art, the beacons produced a single wavelength light which was received by a video camera with a solid state imager. Then a calculation of the centroid of the received image from each beacon was made and from known formulas, the location of the camera with regard to the beacon was determined. Since the beacon is mechanically connected to one object of interest and since the camera is connected to the other object of interest it is then possible to compute the distance or range of one object relative to the other. The range accuracy is a function of how accurately the centroids are determined.